/*
    * Copyright 2012 smartics, Kronseder & Reiner GmbH
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package de.smartics.ci.config.load;
  
  import java.io.FileNotFoundException;
  import java.io.IOException;
  
  import org.jdom.Document;
  import org.jdom.Element;
  import org.jdom.JDOMException;
  import org.jdom.input.SAXBuilder;
  import org.jdom.xpath.XPath;
  import org.xml.sax.InputSource;
  
  import de.smartics.ci.config.hudson.AbstractHudsonConfigHelper;
  import de.smartics.ci.config.utils.JDomUtils;
  import de.smartics.util.lang.Arguments;
  import de.smartics.util.lang.NullArgumentException;
  
  /**
   * Loader of XML job configurations.
   */
  public final class HudsonJobConfigLoader
  {
    // ********************************* Fields *********************************
  
    // --- constants ------------------------------------------------------------
  
    // --- members --------------------------------------------------------------
  
    /**
     * The location manager to load resources.
     */
    private final LocationManager locationManager;
  
    /**
     * The loader configuration to control the loading and creation of Hudson job
     * configuration files.
     */
    private final HudsonJobConfigurationLoaderConfig loaderConfig;
  
    /**
     * Helper to merge Hudson XML config files.
     */
    private final DocumentMerger merger = new DocumentMerger();
  
    // ****************************** Initializer *******************************
  
    // ****************************** Constructors ******************************
  
    /**
     * Default constructor.
     *
     * @param locationManager the location manager to load resources.
     * @param loaderConfig the loader configuration to control the loading and
     *          creation of Hudson job configuration files.
     * @throws NullArgumentException if {@code locationManager} or
     *           {@code loaderConfig} is <code>null</code>.
     */
    public HudsonJobConfigLoader(final LocationManager locationManager,
        final HudsonJobConfigurationLoaderConfig loaderConfig)
      throws NullArgumentException
    {
      Arguments.checkNotNull("locationManager", locationManager);
      Arguments.checkNotNull("loaderConfig", loaderConfig);
  
      this.locationManager = locationManager;
      this.loaderConfig = loaderConfig;
    }
  
    // ****************************** Inner Classes *****************************
  
    // ********************************* Methods ********************************
  
    // --- init -----------------------------------------------------------------
  
    // --- get&set --------------------------------------------------------------
  
    // --- business -------------------------------------------------------------
  
    /**
     * Loads the XML document from the given loader plan. The loader plan
     * instructs the job config loader to load a number of Hudson job
     * configuration files to merge their contents.
     *
     * @param plan the plan to load a number of job config files in a given order.
    *          Later config files override values previously loaded.
    * @return the document containing the merged information from the job config
    *         files specified by the plan as an XML string.
    * @throws NullArgumentException if {@code plan} is <code>null</code>.
    * @throws IllegalArgumentException if {@code plan} is empty.
    * @throws JDOMException on any XML parsing or generation problem.
    */
   public HudsonJobConfig loadHudsonConfig(final LoaderPlan plan)
     throws NullArgumentException, IllegalArgumentException, JDOMException
   {
     final Document document = load(plan);
     final String xmlString = JDomUtils.toString(document);
     final String id = fetchId(document);
     return new HudsonJobConfig(id, xmlString);
   }
 
   private String fetchId(final Document document) throws JDOMException
   {
     final Element projectIdElement =
         (Element) XPath.selectSingleNode(document,
             "/maven2-moduleset/authToken");
     final String projectId = projectIdElement.getTextNormalize();
     return projectId;
   }
 
   /**
    * Loads the XML document from the given loader plan. The loader plan
    * instructs the job config loader to load a number of Hudson job
    * configuration files to merge their contents.
    *
    * @param plan the plan to load a number of job config files in a given order.
    *          Later config files override values previously loaded.
    * @return the document containing the merged information from the job config
    *         files specified by the plan as an XML string.
    * @throws NullArgumentException if {@code plan} is <code>null</code>.
    * @throws IllegalArgumentException if {@code plan} is empty.
    * @throws JDOMException on any XML parsing or generation problem.
    */
   public Document load(final LoaderPlan plan) throws NullArgumentException,
     IllegalArgumentException, JDOMException
   {
     checkArguments(plan);
 
     Document document = createDocument(plan);
 
     String resource = null;
     try
     {
       for (final String configName : plan)
       {
         resource = configName + ".xml";
         final InputSource inputSource = locationManager.open(resource);
         document = mergeDocument(document, inputSource);
       }
 
       final HudsonJobDocumentFixer fixer =
           new HudsonJobDocumentFixer(loaderConfig, document);
       fixer.fix();
 
       return document;
     }
     catch (final FileNotFoundException e)
     {
       throw new IllegalArgumentException("Resource '" + resource // NOPMD
                                          + "' cannot be found.", e);
     }
     catch (final JDOMException e)
     {
       throw new IllegalArgumentException("Resource '" + resource
                                          + "' is not valid.", e);
     }
     catch (final IOException e)
     {
       throw new IllegalArgumentException("Resource '" + resource
                                          + "' cannot be read.", e);
     }
   }
 
   private static void checkArguments(final LoaderPlan plan)
     throws IllegalArgumentException, NullArgumentException
   {
     Arguments.checkNotNull("plan", plan);
 
     if (plan.isEmpty())
     {
       throw new IllegalArgumentException("The loader plan must not be empty.");
     }
   }
 
   private Document createDocument(final LoaderPlan plan) throws JDOMException
   {
     final Document hudsonConfigXml =
         AbstractHudsonConfigHelper.createDocument();
     final MavenInfoApplier maven = new MavenInfoApplier(loaderConfig, plan);
     maven.addAllInfo(hudsonConfigXml);
     return hudsonConfigXml;
   }
 
   private Document mergeDocument(final Document document,
       final InputSource inputSource) throws JDOMException, IOException
   {
     final SAXBuilder builder = new SAXBuilder();
     final Document newDocument = builder.build(inputSource);
     final Document mergedDocument = merger.merge(document, newDocument);
 
     return mergedDocument;
   }
 
   // --- object basics --------------------------------------------------------
 
 }